In general, as one of the countermeasures against the exhaust gas of the internal combustion engine such as a gasoline engine and LPG engine, the EGR (exhaust gas recirculation system) which is designed to reduce NOx by lowering the combustion temperature by mixing the exhaust gas with intake air has been broadly adopted.
Further, as the bearing for a reciprocating shaft (hereinafter, referred to as a stainless shaft) made of an austenitic stainless steel operating the recirculation exhaust gas flow rate control valve provided to a exhaust gas taking pipe line of the EGR, there is known a bearing made of sintered Cu alloy with a composition consisting of Ni: 10 to 30%, Sn: 5 to 12%, C: 3 to 10%, and Cu and inevitable impurities as the balance, and having a structure in which free graphite is dispersed and distributed into the base of a Cu—Ni—Sn based solid solution (for example, see Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2004-68074